Prior artisans have proposed a wide variety of designs for electric toothbrush housings and handles. Many of these designs provide a collection of ridges extending in a direction either parallel to the longitudinal axis of the housing, such as in U.S. Des. Pat. Nos. 375,204 and 454,251; or generally perpendicular to that axis as in 382,407. In addition to certain aesthetic qualities that a collection of parallel ridges may provide, providing such ridges may also serve to promote gripping of the housing by a user, particularly during use of the toothbrush. Although satisfactory in many respects, collections of ridges along the exterior of a toothbrush may promote build-up of dentifrice and other agents over a period of time within crevices along the ridges. Accordingly, housing designs that emphasize a generally smooth outer surface, are favored.
It has been recognized in the art that improved handle designs for electric toothbrushes are needed. Proper handling and orientation of an electric toothbrush during use requires a handle contour that is well matched to a user's hand, and a surface having a relatively low tendency for slippage when being grasped. U.S. Pat. No. 6,390,818 addressed the need for an ergonomic grip for a dental instrument. However, that device is for a sleeve that may be fitted over a dental tool, such as may be used by a dental professional. And so, that device is not readily applicable to the field of electric toothbrushes, and particularly those that are directed for widespread retail sale to consumers.
Although the design of the '818 patent is satisfactory in many respects, other artisans have proposed different housing designs. Many of these designs utilize a flat region along a portion of the housing length. A flat region may facilitate gripping of the housing since such region disrupts the otherwise smooth contour of the otherwise cylindrical housing. However, depending upon the orientation of the brush head, such a flat region may actually hinder gripping of the housing. Furthermore, the orientation of the flat region with respect to the brush head may or may not be desirable depending upon which hand the user is holding the brush with. Examples of such housings with one or more flat regions include U.S. Des. Pat. Nos. 453,626 and 454,695. Accordingly, a need remains for an improved housing for an electric toothbrush.